1. Field of the Invention
The invention relates to novel polymer/polyol compositions that are reactive with polyisocyanates to produce polyurethane products. The invention also relates to novel methods for making such compositions and to methods for making polyurethane products therefrom.
2. Description of the Prior Art
Polymer/polyol dispersions have been and currently are being used in the production of polyurethane products. Such dispersions result in polyurethane products having a wide variety of desirable properties.
There are a number of prior art disclosures relating to the production of polymer/polyol dispersions including the Stamberger patents, U.S. Pat. Nos. 3,304,273; 3,383,351; Re. 29,118 (reissue of 3,304,273) and Re. 28,715 (reissue of 3,383,351); the Stamberger British Pat. No. 1,022,434; the Scharf et al. and Kuryla Canadian Pat. Nos. 735,010 and 785,835; the Pizzini et al. U.S. Pat. No. 3,823,201; Re. 29,014 (reissue of 3,823,201); the Ramlow et al. U.S. patent application, Ser. No. 431,080, filed Jan. 7, 1974; the Ramlow et al. patent U.S. Pat. No. 3,953,393; the DeWald U.S. Pat. No. 3,655,553; and Japanese Patent JA 52005887 (Application No. 8099/1975, Laid Open No. 5887/1977).
Each of these prior art disclosures beginning with the Stamberger patents describes the production of polymer/polyol dispersions by polymerizing one or more ethylenically unsaturated monomers in situ in a polyol to form dispersions of small polymer particles dispersed in the polyol. The dispersions are then mixed with polyisocyanate and other polyurethane-forming reagents and reacted to form the polyurethane product and serve as a convenient, efficient and economical means for improving resultant polyurethane properties. This procedure and the resulting polymer/polyol dispersions have been widely accepted by the polyurethane industry and continue to be extensively used throughout the industry.
While the prior art polymer/polyol dispersions have found extensive use throughout the polyurethane industry, the development of more sophisticated, higher speed and larger volume equipment, machines and systems for handling, mixing and reacting the polyurethane-forming ingredients have created the need for improvements in polymer/polyol dispersions. The need for more stable dispersions has developed so that they can be stored until used without undergoing any significant settling. At one time there was not much concern for the seediness, viscosity or filterability of polymer/polyols in actual commercial practice. However, the state of the art of polyurethane production now has advanced to the point where these considerations are very important. There is now much concern with filterability, seediness, and viscosity because of the more sophisticated machine systems now in use for large volume production. Also, the prior art dispersions could not be made in highly stable condition with the relatively low molecular weight polyols such as dipropylene glycol, thus rendering the lower molecular weight materials less desirable than the higher molecular weight materials as a polyol component of polymer/polyol dispersions. The lower molecular weight polyols, however, are of value in those instances where low viscosity is essential and for foams, coatings, adhesives and some types of sealants.
The present invention provides highly stable and highly filterable polymer/polyol compositions which are low in, or substantially free of, seediness. It provides better dispersion stability than can be obtained by earlier procedures and/or eliminates or minimizes the expenses and hazards or difficulties accompanying some of the earlier techniques. The present invention also provides means for providing highly stable or reasonably stable polymer/polyol compositions having high polymer contents by using relatively small amounts of stable preformed polymer/polyols having low to moderate polymer contents which are easier to make. It also permits a wider selection of polyols, polymer compositions and polymer contents to be used in the manufacture of stable polymer/polyol compositions. It also permits the use of base polyols of lower viscosities and/or preformed polymer/polyols of lower viscosities. It also permits comparatively higher polymer contents in the dispersion at lower viscosities without impairing stability. These and other advantages are obtained by employing a blend of base polyol and a relatively small amount of a more stable preformed polymer/polyol prior to mixing with the monomer or monomers for the in situ polymerization.
The use of polyol blends to produce polymer/polyols has been disclosed by the above-identified Stamberger, Scharf et al., Kuryla, Pizzini, Ramlow et al. and DeWald patents and the Ramlow et al patent application. The use of low molecular weight polyols in polymer/polyol dispersions is mentioned in the Stamberger British patent. However, nowhere in any of these references is there any disclosure or suggestion of the discovery of the advantages of the present invention by the use of blends containing a small amount of a more stable preformed polymer/polyol and a major amount of the base polyol for the production of stable polymer/polyol compositions as described and claimed herein.
The DeWald patent discloses that the polyol is preferably a triol but can contain as much as 40 percent of a diol or tetrol having the same molecular weight range. The molecular weights of the polyols do not exceed 5500, are preferably no more than 5000 and are advantageously in the range of 1500-5000 and preferably 3000-5000.
The Pizzini patent discloses the use of a polyol blend consisting of two polyols having the same molecular weights. The Ramlow et al. patent application discloses the preparation of polymer/polyol dispersions from polyol blends and vinyl or vinylidene halogenide monomers and alleges improvements in stability.
The Ramlow et al. patent discloses the preparation of polymer/polyol dispersions by polymerizing vinyl monomers in the presence of alkyl mercaptans as chain transferring agents in specially formulated, unsaturation-containing polyols containing specified, and allegedly critical, amounts of unsaturation.
The Japanese patent discloses the manufacture of polymer/polyols using modified polyols, i.e., polyesters, formed by reacting a mixture of saturated and unsaturated dibasic organic acid with a polyol. A vinyl type monomer, e.g., styrene, is then polymerized in situ in the resulting modified polyol or polyester. The resulting polymer/polyol is used in the manufacture of polyurethanes.
None of the prior art references mentioned above and no prior art is known which discloses, teaches or suggests stable polymer/polyols having the advantageous properties of the compositions of this invention prepared from ethylenically unsaturated monomers by the use of blends of a large amount of a polyol having a number average molecular weight of at least about 76 and a small amount of a preformed polymer/polyol as described herein.